Stop-start control apparatus of internal combustion engine, and control method thereof

ABSTRACT

In an eco-run control, determination of a stop of an internal combustion engine ( 1 ) is reliably and promptly made. An internal combustion engine stop-start control apparatus for executing a control of stopping the internal combustion engine ( 1 ) upon satisfaction of a predetermined stop condition, and for executing a control of starting the internal combustion engine ( 1 ) upon satisfaction of a predetermined start condition, has: stop request determination means (step S 1 ) for determining that there is a request for stopping the internal combustion engine ( 1 ) based on satisfaction of the stop condition; and stop determination means (steps S 2 , S 4 ) for determining a stop of the internal combustion engine ( 1 ) based on a state of a predetermined physical quantity that changes in relation to operation of the internal combustion engine ( 1 ), the state occurring within a predetermined determination time (Ten), and for setting the determination time (Ten) shorter if the request for stopping the internal combustion engine ( 1 ) is present than if the request is absent.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a control apparatus for automatically stoppingor starting an internal combustion engine, such as a gasoline engine, adiesel engine, or the like, upon satisfaction of a predeterminedcondition. More particularly, the invention relates to a controlapparatus for making a determination regarding a stop of an internalcombustion engine, and a control method of the apparatus.

2. Description of the Related Art

An internal combustion engine installed in a vehicle is stopped not onlydue to an intentional stop operation, but also due to a fuel shortage,an excessive drop in engine rotation speed, etc. Lately, an internalcombustion engine is also stopped by a generally termed eco-run controlof stopping the engine at a stop of the vehicle for the purpose ofimproving fuel economy. A technology in which an engine is stopped bythe eco-run control is described in Japanese Patent ApplicationLaid-Open No. 11-324755. According to the technology described in thislaid-open patent application, at the time of an automatic run of theengine caused upon satisfaction of a predetermined condition, thestandby time prior to execution of the automatic engine stop is changedin length in accordance with the magnitude of the braking operationforce occurring during the state in which the condition is satisfied.

If the engine is stopped due to an automatic stop based on a generallytermed stop control, or due to other causes, various controls associatedwith the stop are usually performed. Furthermore, as described in theaforementioned patent application, in the eco-run control, the engine isrestarted when the satisfaction of the condition discontinues.Therefore, the determination regarding a stop of the engine needs to beperformed electrically or mechanically.

Many conventional internal combustion engines employ a sensor thatoutputs a pulse signal at every predetermined rotational angle of anoutput shaft, for example, a crankshaft or the like, as a device fordetecting the engine rotation speed. In this kind of internal combustionengine, the use of the sensor makes it possible to determine whether theengine has stopped. That is, if the engine rotation speed decreases, thepulse signal interval or the pulse width becomes long, and the durationfrom the time point of input of the previous signal to the time point ofinput of the next signal (generally termed update time) becomes long. Ifthe engine stops, the pulse signal is no longer updated. Therefore, anengine stop can be determined at a time point at which the elapsed timefrom the previous signal update reaches a predetermined length of time.

[Problems To be Solved]

As described above, the engine stops for various factors. The behaviorof engine operation occurring until the engine rotation stops variesfrom one stop factor to another. For example, if the engine comes to astall due to an abnormality or a trouble, the change in engine rotationspeed is not monotonous, but the engine rotation speed changes in agenerally termed oscillating manner in which the rotation speed repeatsincreases and decreases until the engine finally stops. In this case,even if the pulse signal update time increases with the decreasingengine rotation speed during the process from the start of decrease inrotation speed until a stop of the engine, it is impossible toimmediately determine whether the increased update time is a result of astop of the engine or is merely an increased update time preceding astop.

Therefore, the time allowed before determining a stop of the engine isset long in order to ensure reliable determination of a stop of theengine regardless of the kind of stop factor. That is, determination ofa stop of the engine is made if a predetermined stop determination timeelapses without update of the pulse signal.

In the aforementioned eco-run control, the engine stop control isperformed upon satisfaction of a predetermined stop condition. If afterthat, a vehicle start request is made, the satisfaction of thepredetermined stop condition discontinues and the engine restart controlis to be performed. In that case, the engine restart control is executedonly after a stop of the engine is determined. Therefore, the restart ofthe engine delays if there is a delay in determination of a stop of theengine.

Therefore, according to the engine stop determination and the subsequentengine restart control in the conventional art, a long time is neededprior to actual restart of the engine if a start request is madeimmediately after the engine stop condition is met in the generallytermed eco-run control. Hence, various drawbacks occur. For example, aresponse delay in the start control causes discomfort, or causeslaggardness.

SUMMARY OF THE INVENTION

The invention has been accomplished in view of the aforementionedtechnical problems. It is an object of the invention to improve therestart performance of an internal combustion engine by promptly andreliably determining a stop of the engine when the engine is to berestarted after being automatically stopped.

In order to achieve the aforementioned object, a first aspect of theinvention provides a vehicle-installed internal combustion enginestop-start control apparatus that executes a control of stopping aninternal combustion engine upon satisfaction of a predetermined stopcondition, and that executes a control of starting the internalcombustion engine upon satisfaction of a predetermined start condition.The control apparatus includes: stop request determination means fordetermining that there is a request for stopping the internal combustionengine based on satisfaction of the stop condition; and stopdetermination means for determining a stop of the internal combustionengine based on a state of a predetermined physical quantity thatchanges in relation to operation of the internal combustion engine, thestate occurring within a predetermined determination time, and for, ifthe request for stopping the internal combustion engine is present,setting the determination time at a time that is shorter than adetermination time set if the request is absent.

In another construction, the stop determination means determines a stopof the internal combustion engine (1) based on elapse of a predeterminedtime from a predetermined time point which relates to operation of theinternal combustion engine if the internal combustion engine is stoppedbased on a request for stopping the internal combustion engine.

Furthermore, in a control method of the above-described controlapparatus, it is determined that there is a request for stopping theinternal combustion engine based on satisfaction of the stop condition.If the request for stopping the internal combustion engine (1) ispresent, the determination time for determining a stop of the internalcombustion engine is set at a time that is shorter than a determinationtime set if the request is absent. It is determined that the internalcombustion engine has stopped, based on a state of a predeterminedphysical quantity that changes in relation to operation of the internalcombustion engine, the state occurring within the determination time.

In another control method, a stop of the internal combustion engine isdetermined based on elapse of a predetermined time from a predeterminedtime point if the internal combustion engine is stopped based on arequest for stopping the internal combustion engine.

The above-described control apparatuses and methods determine that thereis a request for stopping the internal combustion engine, if thepredetermined condition for stopping the internal combustion engine ismet. A state of a suitable physical quantity associated with operationof the internal combustion engine, such as the number of rotations, therate of change in the number of rotations, etc., the state occurringwithin a predetermined determination time, is determined. A stop of theinternal combustion engine is determined based on the aforementionedstate. The determination time differs between the case where the enginestop request is made and the case where stop request is not made.Specifically, the determination time is reduced in the case where theengine stop request is made, in comparison with the other case. As aresult, if the engine stop request is made upon satisfaction of thepredetermined condition, determination of a stop of the engine is madewithin a short time. Therefore, even in a case where after the enginestop control is initiated upon satisfaction of the predeterminedcondition, the engine is started due to discontinuation of thesatisfaction of the condition, the stop of the engine is determined atan early time, so that the engine start control is executed at an earlytime. Therefore, it becomes possible to avoid generally-termedlaggardness or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart illustrating a control performed by a controlapparatus in accordance with the invention.

FIG. 2 is a graph indicating changes in engine rotation speed toward astop of the engine, in the case of an automatic stop and in the case ofa stop caused by an abnormality or the like.

FIG. 3 is a time chart indicating state changes in a case where thecontrol illustrated in FIG. 1 is performed, together with state changesin the case of a conventional art.

FIG. 4 is a flowchart illustrating another control performed by acontrol apparatus in accordance with the invention.

FIG. 5 is a schematic block diagram of a control system of an internalcombustion engine to which the invention pertains.

FIG. 6 is a schematic illustration of a crank angle sensor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the invention will be described below. Firstly,an internal combustion engine to which the invention pertains will bedescribed. The internal combustion engine in accordance with theinvention is an internal combustion engine that can be automaticallystopped and automatically restarted by supplying fuel or air to theengine and stopping the supply thereof, or by performing and stoppingthe fuel ignition. Examples of the engine include diesel engines,gasoline engines, engines that use a gas as a fuel, etc. FIG. 5 shows adiesel engine as an example of an internal combustion engine (engine) 1.The engine 1 is a generally termed direct injection-type engine in whichfuel is injected directly into cylinders 2, 3, 4, 5. The engine 1 isequipped with an exhaust gas recirculating mechanism (EGR) for exhaustemission control.

That is, each cylinder 2, 3, 4, 5 is provided with an injector 6, 7, 8,9 that injects fuel at high pressure. These injectors 6, 7, 8, 9 areconnected to a common rail 10 that pressurizes fuel and thereforesupplies high-pressure fuel. Each cylinder 2, 3, 4, 5 is provided with aglow plug 11, 12, 13, 14.

An intake manifold 15 that distributes intake air to the cylinders 2, 3,4, 5 is connected to a compressor 17 of an exhaust-type supercharger 16.An intake passage extending from the compressor 17 to the intakemanifold 15 is provided with an intercooler 18 for cooling the intakeair heated by pressurization, and an intake throttle valve 19 forcontrolling the amount of intake. The intake throttle valve 19 isdesigned so that the valve 19 can be electrically controlled by anactuator (not shown) such as an electric motor or the like.

An exhaust manifold 20 connected to exhaust ports of the cylinders 2, 3,4, 5 is connected to an exhaust turbine 21 of the exhaust-typesupercharger 16. The exhaust turbine 21 is connected in communication toa catalytic converter 22 that has an emission control catalyst.

An exhaust gas recirculation passage 23 is provided for conducting aportion of the combustion exhaust gas produced in the cylinders 2, 3, 4,5 to the intake manifold 15. The exhaust gas recirculation passage 23 isprovided with an EGR cooler 24 for cooling exhaust gas and an EGR valve25 for controlling the amount of flow of exhaust gas, in that order fromthe side of the exhaust manifold 20.

The above-described engine 1 is designed so as to allow a generallytermed eco-run control in which the engine is automatically stopped uponsatisfaction of a predetermined condition, for example, a condition thatthe vehicle is at a stop and a braking operation is performed, and theengine is automatically restarted upon discontinuation of thesatisfaction of the stop condition, for example, discontinuation of thebraking operation. For this control, an electronic control unit (ECU) 26is provided.

The electronic control unit 26 is formed mainly by a microcomputer. Theengine electronic control unit 26 is designed so as to performcomputation based on input data, and to execute a control for stoppingthe engine 1 and a control for restarting the engine 1 based on resultsof computation. The control for stopping the engine 1 is, for example, acontrol that closes the intake throttle valve 19 and the EGR valve 25,and stopping fuel injection. The control for restarting the engine 1 is,for example, a control that opens the intake throttle valve 19, andcranks the engine 1 by driving a starter (not shown), and injects fuelin accordance with the cranking of the engine 1.

In order to perform these controls, an accelerator operation amountsensor 27 and a crank angle sensor 28 are connected to the electroniccontrol unit 26. Although not indicated in the drawings, signalsindicating other physical quantities, such as vehicle speed signals andthe like, are input to the electronic control unit 26.

The crank angle sensor 28 is a sensor for detecting the crank angle inorder to determine a cylinder where fuel injection is to be performed.As shown in FIG. 6, the crank angle sensor 28 has an angle plate 29mounted on an output shaft of the engine 1, and a pickup 30 disposed ata predetermined position radially outward of the angle plate 29. Theangle plate 29 is a disc-shaped or gear-shaped member that has, on itsouter peripheral edge, protrusions or teeth formed at everypredetermined angle (e.g., every 10 degrees). The pickup 30 is agenerally termed electromagnetic pickup that is designed so as to outputa signal every time a protrusion or tooth of the angle plate 29approaches and moves apart from the pickup. The signal output from thepickup 30 is processed into a pulse signal by the electronic controlunit 26. The electronic control unit 26 is designed so as to detecting acrank angle or detecting the number of rotations of the engine 1 or therotation speed thereof, by counting (or updating) the pulse signals.

Examples of the aforementioned physical quantity that changes withoperation of the engine 1 are the rotational angle of the engine 1 andthe state of the pulse signal occurring within a predetermined time. Onthe basis of such a physical quantity, it is determined whether theengine 1 has stopped. The determination regarding an engine stop isperformed in different manners for a case where there is a request for astop of the engine 1 in the generally termed eco-run, and a case wherethe engine stop request is not present.

FIG. 1 is a flowchart illustrating an example of the aforementioned stopdetermining control. Firstly in this control, it is determined whetherthere is an engine stop request in the eco-run control (step S1). Theeco-run control includes a control that stops the engine 1 by stoppingthe supply of fuel to the engine 1 so as to improve fuel economy, uponsatisfaction of a predetermined stop condition, such as a condition thatthe vehicle is at a stop and the braking of the vehicle is executed witha brake pedal depressed, or the like. In step S1, it is determinedwhether a request for a stop of the engine 1 is output by the electroniccontrol unit 26 in association with satisfaction of the aforementionedstop condition.

If the engine stop request in the eco-run control is present andtherefore determination is affirmatively made in step S1, an eco-runcontrol time Tec is adopted as a predetermined time Ten for determininga stop of the engine 1 (engine stall determination time) (step S2).Conversely, if the engine stop request in the eco-run control is notpresent and therefore determination is negatively made in step S1, anormal time Tod is adopted as a predetermined time Ten for determining astop of the engine 1 (engine stall determination time) (step S3).

The engine stall determination time Ten is a time that elapses fromattainment of predetermined state of the aforementioned physicalquantity to determination of an engine stall. More specifically, theengine stall determination time Ten is a time that elapses withoutupdate of the pulse signal by the crank angle sensor 28, or a timecorresponding to the pulse width of the pulse signal.

The eco-run control determination time Tec is set shorter than thenormal determination time Tod. The reason for this setting is statedbelow.

FIG. 2 is a diagram schematically indicating changes in the rotationspeed of the engine 1 preceding a stop of the engine 1. In FIG. 2, abroken line indicates a case where the engine 1 is stopped by theeco-run control, and a solid line indicates a case where the engine 1 isstopped due to an abnormality, such as a fuel shortage or the like. Inthe case of a stop the engine 1 due to the eco-run control, satisfactionof a predetermined condition, such as a condition that the vehicle is ata stop and a braking operation is performed, or the like, triggersexecution of a control of closing the intake throttle valve 19 and thenstopping fuel injection, so that the rotation speed of the engine 1decreases at a substantially constant rate (i.e., linearly). Incontrast, in the case of an engine stall based on an abnormality, intakeis still provided and fuel injection is performed, so that the enginerotation speed does not stably decrease (i.e., linearly) but thedegreasing tendency of rotation speed changes during the decrease insome cases.

Thus, as for the stop of the engine 1 caused by the eco-run control, theengine 1 unfailingly stops at the elapse of a predetermined time. Thatpredetermined time or a time determined on the basis of thecharacteristic of the stop caused by the eco-run control (that therotation speed decreases at a substantially constant rate) is set as adetermination time Tec. Although the determination time Tec is shorterthan the normal determination time Tod, a stop of the engine 1 can bedetermined without an error.

After the engine stall determination time Ten is set as Tec or Ten instep S2 or S3, an engine stop is determined (step S4) if the outputsignal of the crank angle sensor 28 (or the aforementioned pulse signal)is not updated despite elapse of the determination time Tec or Tod.Therefore, in the case where the engine 1 is stopped by the eco-runcontrol, a stop of the engine 1 can be determined without a delaybecause the determination time Tec is relatively short.

FIG. 3 is a time chart from a stop to a restart of the engine. Regardingthe restart control indicated in a latter half of the chart, a controlin accordance with the invention is indicated by a broken line, and acontrol in accordance with the conventional art is indicated by a solidline. In the chart, a fine line indicates the degree of opening of theintake throttle valve, and a bold line indicates the engine rotationspeed. As for the vertical axis of the chart, upper points along theaxis indicate higher engine rotation speeds and less degrees of openingof the intake throttle valve. If the engine stop request based on theeco-run control is output at a time point t1, the engine stop control iscorrespondingly initiated at a time point t2. Specifically, the intakethrottle valve 19 is operated toward the constriction side, that is, thedegree of opening of the valve is reduced. At a time point t3 when theintake throttle valve 19 becomes substantially completely closed, thefuel injection is stopped, so that the engine rotation speed begins todecrease.

After that, at a time point t4, the update of the signal from the crankangle sensor 28 or the update of a pulse signal based on the signal fromthe crank angle sensor 28 stops. In the control apparatus of theinvention, it is determined that the engine 1 has stopped, on conditionthat the aforementioned signal update does not occur within a period offrom the time point t4 to a time point t5 that comes at the elapse ofthe determination time Tec from the time point t4. In the invention,this determination (that the engine 1 has stopped) is made at the timepoint t5, the engine 1 can be restarted immediately after the time pointt5. Therefore, as the engine restart control is initiated immediatelyafter t5, the degree of opening of the intake throttle valve begins toincrease from the substantially completely closed state. At a time pointt6, the engine 1 starts to turn. Then, the rotation speed of the engine1 begins to increase.

Therefore, according to the control apparatus of the invention, if theengine restart request is made at the time point of determination of astop of the engine 1 or immediately after the time point, the controlfor restarting the engine 1 can be initiated immediately after the timepoint t5 of determination of the stop of the engine 1.

In the conventional art, in contrast, the determination regarding a stopof the engine during the eco-run control and the determination regardinga stop of the engine during a normal operation are performed not indistinguished manners but in the same manner. Therefore, in the case ofFIG. 3, the conventional art determines the stop of the engine 1 at atime point t7 that comes at the elapse of the normal determination timeTod, which is longer than the eco-run control-purpose determination timeTec, from the time point t4. Therefore, the restart of the engine 1 isnot performed until a late time point t8.

Thus, in the case of stopping the engine 1 based on the eco-run control,the control apparatus of the invention determines the stop of the engine1 without a delay. Therefore, even if the engine restart request is madeimmediately after satisfaction of a condition for automatically stoppingthe engine 1, the control apparatus is able to avoid or reduce the delayin initiating the engine restart control. As a result, the controlapparatus of the invention achieves good responsiveness in the controlof automatically stopping and automatically starting the engine 1, andtherefore is able to prevent discomfort, such as laggardness in vehiclebehavior, or the like.

Another embodiment of the invention will be described. In the case of anengine automatic stop control in which, for example, the degree ofopening of the intake throttle valve 19 is reduced and the fuelinjection is stopped, the rotation speed of the engine 1 linearlydecreases as indicated in FIG. 2. Since the automatic stop control ofthe engine 1 is initiated during an idling state of the engine 1, theengine rotation speed starts to decrease from an idling rotation speedduring the automatic stop control. Therefore, the engine 1 substantiallyreliably stops at a predetermined time after the initiation of theautomatic stop control. Hence, it is possible to determine a stop of theengine 1 based only on elapse of time, without factoring in changes in aphysical quantity associated with operation of the engine 1.

FIG. 4 is a flowchart illustrating a control in accordance with theembodiment. In this control, if it is determined in step S1 that thereis an engine stop request based on the eco-run control, it is determinedin step S11 whether the elapsed time T1 from a predetermined referencetime point has reached a reference time τ. The reference time point maybe, for example, a time point of output of the engine stop request basedon the eco-run control, a time point of initiation of the automatic stopcontrol of the engine 1, a time point of stop of fuel injection, etc.The reference time τ is a time set through actual measurement beforehandas a time that elapses from the reference time until stop of the engine1. Instead of the time predetermined individually for engines, theengine 1 may be a map value set in accordance with data, such as adegrease gradient (rate of change) of engine rotation speed occurringafter the fuel injection stops, or the like.

If the determination in step S11 is negatively made, the process returnsto continue the existing control. If the determination in step S11 isaffirmatively made, an engine stop is determined (step S12).

If the determination in step S1 is negatively made, that is, if theautomatic stop of the engine 1 based on the eco-run control is not thecase, the time Tec for determination of a stop of the engine 1 is set asthe normal determination time Tod, as in the control process illustratedin FIG. 1. That is, a stop of the engine 1 is determined at a time pointwhen the elapsed time from the time point of absence of the signalupdate reaches the normal determination time Tod (step S4).

This construction intended to execute the control illustrated in FIG. 4is also able to reduce the time needed for determination of a stop ofthe engine 1 while avoiding a false determination as behavior of theengine 1 smoothly or linearly changes toward a stop of the engine duringthe automatic stop control of the engine 1. As a result, the automaticstop of the engine 1 and the immediately subsequent restart of theengine 1 during the generally termed eco-run control can be smoothlyexecuted without a considerably delay time. Thus, it is possible toprevent discomfort, such as laggardness associated with a delay inengine startup, or the like.

The relationships between the foregoing embodiments and the inventionwill be briefly described below. The functional means of step S1illustrated in FIGS. 1 and 4 correspond to the stop requestdetermination means in the invention. The functional means of steps S2and S4 in FIG. 1 correspond to the stop determination means. Thefunctional means of steps S11 and S12 in FIG. 4 correspond to the stopdetermination means.

The invention is not limited to the foregoing embodiments. For example,if the fuel injection is stopped by the engine stop control, the stopdetermination may be performed based on the crankshaft rotation speedintegrated value acquired with reference to the final fuel injection asthe initiation point of integration. That is, if the number of rotationof the crankshaft (i.e., integrated value of rotation angle) occurringfrom the last injection to the stop of rotation of the crankshaft isless than or equal to a predetermined number of rotations, it isdetermined that the engine stop is a stop based on the eco-run control.If the number of rotation of the crankshaft occurring from the lastinjection to the stop of rotation of the crankshaft is greater than thepredetermined number of rotations, it is determined that the engine 1 isnot a stop based on the eco-run control, but is a stop caused by enginestall or the like.

The physical quantity that changes in association with operation of theinternal combustion engine in the invention is not limited to the pulsesignal generated in relation to the rotation of the crankshaft, but mayalso be a physical quantity that changes in relation to the pistonposition of the internal combustion engine, changes in an image inrelation to operation of an operating member of the internal combustionengine, etc.

[Advantage of the Invention]

As is apparent from the foregoing description, in the case of anautomatic stop of an internal combustion engine upon satisfaction of apredetermined condition, the control in accordance with the inventiondetermines a state of a suitable physical quantity related to operationof the internal combustion engine, such as the number of rotations (orrotation speed), the rate of change thereof, etc., the state occurringwithin a predetermined determination time. The control determineswhether the engine has stopped based on the state of the physicalquantity. The determination time is reduced in the case where an enginestop request is made, in comparison with the other cases. As a result,if an engine stop request is output upon satisfaction of a predeterminedcondition, a stop of the engine is determined within a reduced time.Therefore, even in a case where after the engine stop control isinitiated subsequently to the satisfaction of the predeterminedcondition, the satisfaction of the predetermined condition discontinuesand the engine is to be restarted, the engine start control is executedearly due to the early determination of the stop of the engine. Thus,the control of the invention is able to avoid generally-termedlaggardness.

Furthermore, if the predetermined condition for stopping the internalcombustion engine is met, a request for stopping the engine is made, andthe engine stop control is executed upon the stop request. Therefore,behavior of the internal combustion engine changes toward a stop, andthe change is fixed depending on the type of internal combustion engine,the content of the stop control, etc. Then, the stop of the internalcombustion engine is determined based on the elapse of a predeterminedtime set in accordance with the behavior change toward the stop. Thepredetermined time does not include a holding time for an uncertainstate that occurs in the case where the internal combustion engine stopsdue to an abnormality. Therefore, the predetermined time can be setrelatively short. Hence, it becomes possible to determine a stop of theengine at an early stage.

Still further advantages are achieved. That is, if upon a stop request,the rotation speed of the internal combustion engine decreases at agreat rate, that is, sharply decreases, the predetermined time fordetermining a stop of the engine is short, so that the stop of enginecan be determined at a still early stage. Therefore, the control of theinvention is able to avoid or reduce the delay in determination of astop of the engine or restart of the engine.

1. A vehicle-installed internal combustion engine stop-start controlapparatus that executes a control of stopping an internal combustionengine upon satisfaction of a predetermined stop condition, and thatexecutes a control of starting the internal combustion engine uponsatisfaction of a predetermined start condition, the control apparatus,comprising: stop request determination portion which determines thatthere is a request for stopping the internal combustion engine based onsatisfaction of the stop condition; and stop determination portion whichdetermines a stop of the internal combustion engine based on a state ofa predetermined physical quantity that changes in relation to operationof the internal combustion engine, the state occurring within apredetermined first determination time, and for, if the request forstopping the internal combustion engine is present, setting the firstdetermination time at a time that is shorter than a second determinationtime set if the request is absent.
 2. The control apparatus according toclaim 1, wherein the physical quantity is a rotation angle of an outputshaft of the internal combustion engine.
 3. The control apparatusaccording to claim 1, wherein the state is a state where the rotationangle of the output shaft within the first determination time is equalto, or less than a predetermined rotation angle.
 4. The controlapparatus according to claim 2, wherein the state is a state where thepulse signal is not outputted within the determination time.
 5. Thecontrol apparatus according to claim 2, wherein the state is a statewhere the rotation angle of the output shaft within the determinationtime is equal to, or less than a predetermined rotation angle.
 6. Thecontrol apparatus according to claim 1, further comprising a crank anglesensor for detecting an angle of an output shaft of the internalcombustion engine, wherein the physical quantity is a pulse signaloutput from the crank angle sensor.
 7. The control apparatus accordingto claim 1, wherein the state is a state where the pulse signal is notoutputted within the first determination time.
 8. The control apparatusaccording to claim 1, wherein the stop condition is a condition that avehicle is at a stop and a brake operation of the vehicle is executed.9. A vehicle-installed internal combustion engine stop-start controlapparatus that executes a control of stopping an internal combustionengine upon satisfaction of a predetermined stop condition, and thatexecutes a control of starting the internal combustion engine uponsatisfaction of a predetermined start condition, the control apparatus,comprising: stop request determination portion which determines thatthere is a request for stopping the internal combustion engine based onsatisfaction of the stop condition; and stop determination portion whichdetermines a stop of the internal combustion engine based on elapse of apredetermined time from a predetermined time point if the internalcombustion engine is stopped based on a request for stopping theinternal combustion engine, wherein the predetermined time is set basedon data including at least a degree of decrease in a number of rotationsof the internal combustion engine.
 10. The control apparatus accordingto claim 9, wherein the predetermined time is a time that elapses untilthe internal combustion engine is brought to a stop from an idling stateof the internal combustion engine based on satisfaction of the stopcondition.
 11. The control apparatus according to claim 9, wherein thepredetermined time point relates to the control of stopping the internalcombustion engine.
 12. The control apparatus according to claim 11,wherein the predetermined time point is one of: a time point at whichthe request for stopping the internal combustion engine is output, atime point at which a stop control of the internal combustion engine isstarted, and a time point at which fuel injection of the internalcombustion engine is stopped.
 13. The control apparatus according toclaim 9, wherein the stop condition is a condition that a vehicle is ata stop and a brake operation of the vehicle is executed.
 14. Avehicle-installed internal combustion engine stop-start control methodthat executes a control of stopping an internal combustion engine uponsatisfaction of a predetermined stop condition, and that executes acontrol of starting the internal combustion engine upon satisfaction ofa predetermined start condition, the control method comprising the stepsof, determining that there is a request for stopping the internalcombustion engine based on satisfaction of the stop condition, anddetermining a stop of the internal combustion engine based on a state ofa predetermined physical quantity that changes in relation to operationof the internal combustion engine, the state occurring within apredetermined first determination time, and, setting the firstdetermination time if the request for stopping the internal combustionengine is present, the first determination time is shorter than a seconddetermination time if the request is absent.
 15. A vehicle-installedinternal combustion engine stop-start control method that executes acontrol of stopping an internal combustion engine upon satisfaction of apredetermined stop condition, and that executes a control of startingthe internal combustion engine upon satisfaction of a predeterminedstart condition, the control method comprising the steps of, determiningthat there is a request for stopping the internal combustion enginebased on satisfaction of the stop condition, and determining a stop ofthe internal combustion engine based on elapse of a predetermined timefrom a predetermined time point if the internal combustion engine isstopped based on a request for stopping the internal combustion engine,wherein the predetermined time is set based on data including at least adegree of decrease in a number of rotations of the internal combustionengine.